Allen-Bradley 1794-TB3 Terminal Base Unit Overview

The Allen-Bradley 1794-TB3 is a Flex I/O terminal base unit for I/O wiring termination. This component hosts Flex I/O modules and contributes to the backplane formation. The Allen-Bradley 1794-TB3 has three strips of screw clamp terminals for field connections. It provides termination points for I/O signals and power supply devices. The Allen-Bradley 1794-TB3 supports daisy-chaining to nearby Flex I/O modules. This terminal base unit is rated for 120 VAC and 10 Amperes maximum. It draws 640 mA at 5VDC from the FlexBus.

Technical Specifications

General Specifications

• Manufacturer: Rockwell Automation.

• Brand: Allen-Bradley.

• Part Number: 1794-TB3.

• Series: Flex I/O.

• Product Type: Flex I/O Terminal Base Unit.

• Module Type: Terminal Base Unit.

• Connection Type: Screw clamp.

• UPC: 10662468112359.

• UNSPSC: 32151602.

Terminal Specifications

• Number of Terminal Strips: Three (3) strips.

• Number of Terminals: 52 terminals total.

• Number of Terminal Rows: 2 terminal rows.

• Terminal Strip Assignment:

  • Top row (I/O terminals): 16 terminals

  • Middle row (Common terminal): 18 terminals

  • Bottom row (Supply terminal): 18 terminals

• I/O Terminals: Terminals 0-15

• Common/Supply Terminals: Terminals 16-33 (common), terminals 34-51 (voltage +)

• Daisy-Chaining Terminals: C-34 (+) and B-16 (-) for supply in; C-51 (+) and B-33 (-) for supply out

Electrical Ratings

• Voltage Rating: 24V DC/AC, 120V DC/AC

• Maximum Voltage Rating: 132 VAC

• Supply Voltage Range (max): 125V DC/AC, 50/60Hz

• Current Capacity (max): 10 Amperes

• Backplane Current Draw: 640 mA at 5VDC

• FlexBus Current Draw: 640 mA at 5VDC

• Isolation Voltage: 125V continuous

• Channel Isolation: Module based

Mechanical Specifications

• Terminal Screw Torque: 0.56-0.79 Nm (5-7 lb-in)

• Wire Size: 0.34-3.3 mm² (24-16 AWG)

• Conductors (max): 12 gauge or 4 mm²

• Conductors (min): 22 gauge or 0.35 mm²

• Insulation Thickness: 3/64 inch or 1.2 mm

• Dimensions (HxWxD): 94 mm x 94 mm x 69 mm (3.7 in x 3.7 in x 2.7 in)

Temperature Codes

• North America Temperature Code: T4A

• IEC Temperature Code: T4

Environmental Specifications

• IEC-Rated Operational Temperature: -20°C to 70°C (-4°F to 158°F)

• Relative Humidity: 5% to 95% non-condensing

• Operational Shock: 30G

• Vibration: 5G at 10-500Hz

Installation

• Mounting: DIN Rail (hook over top of DIN rail, push to lock)

Certifications

• c-UL-us

• UL

• CSA

• CE

Compatible Modules (Partial List)

The Allen-Bradley 1794-TB3 is compatible with:

• 1794-IA8, 1794-IA8I, 1794-IA16

• 1794-OA8, 1794-OA8I, 1794-OA16

• 1794-IB8, 1794-IB16XT, 1794-IB10XOB6, 1794-IB10XOB6XT

• 1794-IC16, 1794-IG16, 1794-IH16, 1794-IV16

• 1794-OB8, 1794-OB8EP, 1794-OB8EPXT, 1794-OB16, 1794-OB16D, 1794-OB16P, 1794-OB16PXT

• 1794-OC16, 1794-OG16, 1794-OV16, 1794-OV16P

• 1794-OW8, 1794-OW8XT

Physical Specifications

• Product Net Weight: 0.22 kg.

• Gross Weight: 0.35 kg (with packaging).

Installation Guide

Follow these steps to install the Allen-Bradley 1794-TB3 correctly:

1. Position the terminal base at a slightly angled orientation on the DIN rail.

2. Hook the Allen-Bradley 1794-TB3 over the top of the DIN rail.

3. Slide the terminal base hook under the edge of the adapter module.

4. Engage the FlexBus connector while pushing the terminal base tight against the adjacent adapter.

5. Push the terminal base until it aligns and locks onto the DIN rail.

6. Connect field wiring to the appropriate I/O, common, and supply terminals.

7. Use daisy-chaining terminals (C-34/B-16 for supply in; C-51/B-33 for supply out) for multiple bases.

8. Torque screw terminals to 0.56-0.79 Nm (5-7 lb-in) for secure connections of 1794-TB3.

Packaging List

• Allen-Bradley 1794-TB3 terminal base unit (1 unit)

• Anti-static protective bag (1 piece)

• Installation instructions manual (1 copy)

• Product label with catalog number

Frequently Asked Questions (FAQ)

1. How many terminals does the 1794-TB3 provide?
The Allen-Bradley 1794-TB3 provides 52 screw clamp terminals across three terminal strips.

2. What is the voltage rating of this terminal base unit?
This terminal base unit is rated for 120 VAC and 24V DC/AC with a maximum of 132 VAC.

3. Does the 1794-TB3 support daisy-chaining?
Yes, the Allen-Bradley 1794-TB3 supports daisy-chaining through dedicated supply in and supply out terminals.

4. What is the FlexBus current draw of the 1794-TB3?
The FlexBus current draw is 640 mA at 5VDC for backplane power.

5. What certifications does the 1794-TB3 hold?
This terminal base unit holds c-UL-us, UL, CSA, and CE certifications.